From 74a144ce9831c65371f7482fc6ae748872df679d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 10 Jul 2025 11:53:36 +0200
Subject: [PATCH] Require Boost 1.81.0 or higher

Note: this version of Boost was released in December 2022.
---
 src/libexpr/include/nix/expr/symbol-table.hh | 14 +-------------
 src/libexpr/meson.build                      |  1 +
 src/libutil/serialise.cc                     |  4 ----
 3 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/src/libexpr/include/nix/expr/symbol-table.hh b/src/libexpr/include/nix/expr/symbol-table.hh
index 20a05a09d..1249bdb88 100644
--- a/src/libexpr/include/nix/expr/symbol-table.hh
+++ b/src/libexpr/include/nix/expr/symbol-table.hh
@@ -7,12 +7,7 @@
 #include "nix/util/error.hh"
 
 #include <boost/version.hpp>
-#define USE_FLAT_SYMBOL_SET (BOOST_VERSION >= 108100)
-#if USE_FLAT_SYMBOL_SET
-#  include <boost/unordered/unordered_flat_set.hpp>
-#else
-#  include <boost/unordered/unordered_set.hpp>
-#endif
+#include <boost/unordered/unordered_flat_set.hpp>
 
 namespace nix {
 
@@ -214,12 +209,7 @@ private:
      * Transparent lookup of string view for a pointer to a ChunkedVector entry -> return offset into the store.
      * ChunkedVector references are never invalidated.
      */
-#if USE_FLAT_SYMBOL_SET
     boost::unordered_flat_set<SymbolStr, SymbolStr::Hash, SymbolStr::Equal> symbols{SymbolStr::chunkSize};
-#else
-    using SymbolValueAlloc = std::pmr::polymorphic_allocator<SymbolStr>;
-    boost::unordered_set<SymbolStr, SymbolStr::Hash, SymbolStr::Equal, SymbolValueAlloc> symbols{SymbolStr::chunkSize, {&buffer}};
-#endif
 
 public:
 
@@ -287,5 +277,3 @@ struct std::hash<nix::Symbol>
         return std::hash<decltype(s.id)>{}(s.id);
     }
 };
-
-#undef USE_FLAT_SYMBOL_SET
diff --git a/src/libexpr/meson.build b/src/libexpr/meson.build
index f5adafae0..533030359 100644
--- a/src/libexpr/meson.build
+++ b/src/libexpr/meson.build
@@ -41,6 +41,7 @@ boost = dependency(
   'boost',
   modules : ['container', 'context'],
   include_type: 'system',
+  version: '>=1.81.0'
 )
 # boost is a public dependency, but not a pkg-config dependency unfortunately, so we
 # put in `deps_other`.
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 55397c6d4..a74531582 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -194,10 +194,6 @@ size_t StringSource::read(char * data, size_t len)
 }
 
 
-#if BOOST_VERSION >= 106300 && BOOST_VERSION < 106600
-#error Coroutines are broken in this version of Boost!
-#endif
-
 std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
 {
     struct SourceToSink : FinishSink